board: ti: am62x_evm: Add android bootflow

Add Android bootflow support for AM62X SK EVM board with
new android boot method.

To build for AM62x for Android, we use the
am62x_a53_android.config fragment when building A53 bootloaders:

  $ make am62x_evm_a53_defconfig
  $ make am62x_a53_android.config
  $ make

Co-developed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Bryan Brattlof <bb@ti.com>
diff --git a/doc/board/ti/am62x_sk.rst b/doc/board/ti/am62x_sk.rst
index b9d3524..51dab83 100644
--- a/doc/board/ti/am62x_sk.rst
+++ b/doc/board/ti/am62x_sk.rst
@@ -132,6 +132,20 @@
 .. include::  ../ti/k3.rst
     :start-after: .. k3_rst_include_start_build_steps_uboot
     :end-before: .. k3_rst_include_end_build_steps_uboot
+
+* 3.2.1 Alternative build of A53 for Android bootflow:
+
+Since the Android requires many more dependencies, it is disabled by default.
+An extra config fragment should be used to enable Android bootflow support.
+
+.. prompt:: bash $
+
+  export UBOOT_CFG_CORTEXR="${UBOOT_CFG_CORTEXA} am62x_a53_android.config"
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_uboot
+    :end-before: .. k3_rst_include_end_build_steps_uboot
+
 .. am62x_evm_rst_include_end_build_steps
 
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